The following United State Patents are believed to be most closely related to the present invention:
______________________________________ U.S. Pat. Nos.: ______________________________________ 5,086,197 5,075,558 5,075,541 5,009,277 4,975,546 4,885,433 4,853,496 4,845,684 4,809,351 4,806,707 4,804,949 4,751,741 4,532,376 4,364,035 4,141,073 ______________________________________
Many attempts have been made to determine the position of an object in a data space in the form of computer data. Both two dimensional and three dimensional position determining devices now exist. The use of a writing tablet and a stylus is common for inputting hand written data. Most two dimensional devices require contact between the writing tablet and stylus. Three dimensional devices usually do not require contact. They normally use a form of wave energy such as light, electromagnetic, or sonic.
Generally, two relationships exist between the stylus and the writing tablet. The passive stylus/active tablet utilizes a passive stylus interfacing with an active receiving surface (e.g., resistive and capacitive methods), while the active stylus/passive tablet utilizes an active stylus interfacing with a passive surface (e.g., optical, acoustic, tactile, or electromagnetic). A third method using a mechanical linkage such as a pantograph is rarely used.
The passive stylus/active surface method has some significant shortcomings. The most significant is the active surface or tablet itself. In addition to being complex, large, heavy, cumbersome and difficult to transport, it is expensive. It also cannot distinguish between the stylus and another object pressing on it.
The active stylus/passive surface method also has major drawbacks. Most significantly, this method generally requires an awkward tablet in addition to a separate transmitter and receiver (usually in different locations). Further, the transmitted signal can become obscured before reaching the receiver.
Both the passive stylus/active surface active stylus/passive surface methods have the feeling of being unnatural and require a significant adjustment for the user from the conventional pen and paper. The amount and accuracy of information provided by these methods is limited. In addition, some of these methods require a physical connection between the stylus and the tablet. All the methods provide two dimensional information. Some provide three dimensional information. In addition, they may provide one or more, but not all the following information: displacement, rotation, angle to tablet, and velocity. None provide all the information.
In general, the information is input, analyzed, then output. As part of output, the aforementioned methods can provide a hard copy, but they do not provide an original hard copy as part of input. Since the present invention envisions scanning and writing on a surface with a stylus simultaneously and the coordinate information is obtained by scanning the surface, an original hard copy can be produced simultaneously with input.